A 60‐day indoor feeding trial was conducted to evaluate the effects of dietary tryptophan supplementation on growth performances, whole‐body chemical composition, expression of muscle growth‐related genes (MyoD, myogenin and myostatin), and haematological and biochemical responses of juvenile genetically improved farmed tilapia (GIFT). Five corn–soy‐based isonitrogenous and isoenergetic diets were formulated to contain graded levels of dietary tryptophan (2.6, 3.2, 3.7, 4.2 and 4.8 g/kg of diet). Each diet was randomly assigned to triplicate groups of 30 fish (5.3 ± 0.1 g) per experimental unit, which were fed thrice a day (9:00, 13:00 and 17:00 hr). Maximum growth performances and feed utilization were observed in fish fed tryptophan at 3.7 g/kg of diet. There was no significant (p > .05) effect on whole‐body composition and amino acid profile by dietary tryptophan supplementation. However, significant (p < .05) differences were observed in plasma metabolites and the mRNA expression of MyoD, myogenin and myostatin. Serum cortisol level was found significantly lowest in fish fed tryptophan at 3.7 g/kg of diet. Second‐order polynomial regression analysis of weight gain and nitrogen gain against dietary tryptophan levels indicated that the optimum dietary tryptophan requirement for maximum growth and feed utilization of juvenile GIFT tilapia was 3.8 g/kg of diet.

中文翻译：

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尼罗罗非鱼GIOP幼株对膳食L-色氨酸补充的代谢反应

进行了一项为期60天的室内喂养试验，以评估膳食色氨酸补充对生长性能，全身化学成分，肌肉生长相关基因（MyoD，肌生成素和肌生长抑制素）表达的影响。，以及青少年基因改良养殖罗非鱼（GIFT）的血液学和生化反应。配制了五种基于玉米大豆的等氮和等能日粮，其中含有色氨酸的分级水平（日粮2.6、3.2、3.7、4.2和4.8 g / kg）。每种饮食被随机分为三组，每实验单位30条鱼（5.3±0.1 g），每天喂三次三次（9：00、13：00和17:00）。在以3.7 g / kg日粮饲喂色氨酸的鱼中，观察到最大的生长性能和饲料利用率。 膳食色氨酸补充剂对全身成分和氨基酸谱没有显着影响（p > .05）。然而， 在血浆代谢物和MyoD，肌生成素的mRNA表达中观察到显着（p <.05）差异。和肌生长抑制素。饲喂色氨酸的鱼的血清皮质醇水平最低，为3.7 g / kg。体重增加和氮增加对日粮色氨酸水平的二项多项式回归分析表明，幼年GIFT罗非鱼最大生长和饲料利用的最佳日粮色氨酸需求为3.8 g / kg日粮。